


Where I Went Wrong

by EthelPhantom



Category: Batman - All Media Types, Miraculous Ladybug
Genre: Big Brother Jason Is The Best Jason, Cross-Posted on Tumblr, Gen, Humor, Mari and Jay are biological siblings, MariBat, Prank Wars, Pranks and Practical Jokes, Revenge, they are idiots okay
Language: English
Status: Completed
Published: 2020-02-01
Updated: 2020-02-01
Packaged: 2021-02-28 01:14:25
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 1,532
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22515310
Author URL: https://archiveofourown.org/users/EthelPhantom/pseuds/EthelPhantom
Summary: "Do not prank or mess with Marinette Todd-Wayne, especially her laptop, or you'll regret ever being born."That should be a universally known rule if you asked Jason.
Relationships: Marinette Dupain-Cheng | Ladybug & Jason Todd
Comments: 9
Kudos: 499





	Where I Went Wrong

**Author's Note:**

> Regardless of the title, there's no angst here ok. 
> 
> I needed more big brother Jay content so here you go. Have fun!
> 
> Edit: I chose the wrong picture and didn't notice it until it was too late. I'll be changing it in the morning, but for now, you can find it on my Tumblr which is linked in the end notes.  
> Yet another edit: Alright, I changed it, so we're good again.

So, in hindsight, that had probably been one of Jason’s worst ideas in a while. 

It’s not like he realised Pixie was going to make him pay for what he did. That means it couldn’t be his fault, right? 

(Yes, yes it was.)

Never let it be said that Marinette Todd-Wayne was forgiving. 

It all started when Jason decided to put food colouring in Mari’s toothbrush, so when she brushed her teeth the next morning, she freaked out when everything turned red. Tim had asked him if he was sure that had been a good idea when afterwards he couldn’t find his credit card and later found out someone had used it to go to the coffee shop, Aroma Mocha, nearby. Tim had also actually been the one to question whether it had been a good idea when he was doing it, and that’s why he now cursed the Replacement for not stopping him back then. 

A bit later he’d heard Pixie, Cass and Steph talking about the amazing new products in Aroma Mocha. When Mari had shot him a smug smile and Duke had come into his room with the credit card between his fingers (he said he’d found it in the cereal box in the kitchen. When Dick asked how he knew it because the only cereal box there right now was his, Duke bolted), it was clear who exactly had taken it. 

That resulted in Jason stealing her laptop the next time she went out with any of her friends or the family and Jason wasn’t expected to be there. He sneaked in her room, snatched her laptop from the desk and sprinted back to his own room. There he plopped down on his bed and opened the laptop, trying to figure out how exactly he should break into it. After all, he needed to make sure she wouldn’t be able to see something was wrong right away. 

And so began his quest for vengeance. Once he managed to get past Mari’s security (to her credit, it took him quite the while, even with Replacement’s guide on how to do it the fastest with any of the family’s computers if it for any reason was absolutely necessary), he took up on searching through her files and documents. He finally decided on settling with messing with her commission files.

No, he wasn’t going to delete or change anything _in_ said files, no. That would be unnecessary cruel and unfair to both her and her customers. Instead, Jason created a _ton_ of new folders. He’s pretty sure he created at least a hundred new folders inside her commission folder, leaving 18 of them as his little message for his darling baby sister. 

The actual files he knows she wants and needs are also renamed, but they’re called “yeah you found them baby bug” and “this here is your commission stuff” and “Try me I’ll do it again if someone finds my credit card in the cereal box.”

Mari could definitely be a little shit, but Jason was a huge asshole, and that made all the difference in the world right now. 

(Later Jason realised (and learnt) that anyone that was a born Todd was an asshole by nature and Marinette _definitely_ beat her big brother at that, but that was only later.)

In _hindsight_ , he should have left Marinette’s folders and laptop alone. 

As it is, he doesn’t have said hindsight before he faces the consequences so he’s doing it anyway. So, obviously, that means when Jason shuts down the computer, he’s still happy and _gleeful_ and feels victorious.

That… 

Well, that doesn’t last too long. 

The first three days go well. Pixie doesn’t mention the incident so Jason supposes she simply hasn’t noticed. After a week, he starts getting suspicious, because how could it be she didn’t notice at all? And there’s no way she _wouldn’t_ have said something about it if she _had_ seen it. He gets paranoid for a few days, worried his little sister might attack him at any times, even during the time she was supposed to be at school.

Two weeks later, Jason’s mostly forgotten about the whole thing, which was probably a really, really bad idea. Not actively remembering meant no active defense mechanism on when around Marinette, especially not when around Marinette and the rest of the family _and_ inside the Manor. It meant letting his guard down around his dearest little sometimes rather demonic and sinister sister with a golden heart, the smile and presence of an angel and a broken halo hidden behind her back. 

Now _that_ was a mistake he should have never made. 

So, indeed, a fortnight later, he does not notice the door of his bedroom creaking when someone opens it at six in the goddamn morning after a long, _exhausting_ night at patrol. He also doesn’t notice when a small frame sprints towards him, jumps up, only shooting up and ready to fight when 50 kilograms fall on him. At _once._

“Rise and shine, motherfucker!” the bundle of sunshine (and somehow the tone of her voice is smug and the expression she’s wearing on her face is so gleeful and cruel and sinister, but also rather tired — how early did she wake up for this and did she even go to sleep in the first place) on his lap yells into his her. 

So yes. In hindsight, pranking Marinette had proven out to be the worst idea he had ever had and he should have known that, should’ve been expecting it and preparing for it but he _didn’t,_ and now he regretted it. _All_ of it. 

Then, once Jason was properly awake and alert, Marinette yawned and fell on top of him, curling up against his bigger frame and started snoring. She just— she just fell asleep right then and there. Must’ve been quite the night for her too.

The next morning (or, well, a few hours later) Dick and Tim find them cuddling and sleep-murmuring sweet insults to each other. He forces himself not to laugh, records what's happening and gets Tim to do the same. Once they're done with filming, they finally let themselves laugh out loud and slowly distance themselves from the room and the two just in case.

It might have been a good idea, because one irritated, _tired_ Jason was woken up for the second time too early in the morning and not even by his precious, assholish little sister. 

And that meant said irritated, _tired_ Jason growled and started chasing the “motherfucking nosy Dickiebird” and the “goddamn stalking replacement!” down the long hallways. 

It didn’t end there — as the day proceeded, he found his shampoo no longer opened (he managed to open it eventually. By _breaking_ the bottle), his guns were replaced by water guns, and his oreos turned out to be a russian roulette of “is this one of the cookies filled with tooth-paste flavoured, matcha flavoured, angel foodcake flavoured, fucking _tutti-frutti flavoured_ , vinegar, marshmallow or bubbergum flavoured, _or_ is this a proper oreo which no one has touched and the filling is normal?” 

Seriously, the vinegar was the worst because it wasn’t even sweet and it was so overpowering that there was no way Jason could even try to ignore it. 

When Steph asked him couldn’t he just have checked them first or thrown them away after first ten, he nearly snarled. Not because of Steph, but because _he had tried_ ; they all looked the same, smelled the same (how, he had no idea), and less than half were modified so throwing all of them away would have been waste of perfectly good oreos. 

His sister had also apparently replaced _every single one of his leather jackets_ with a size or two too small ones because they were too small and there was no way he’d just outgrown them. 

She also knew he’d never back down from a dare, and at the end of the day, when just about everyone had gone to sleep (or patrol, or just far from the vengeful Marinette Todd, because being this kind of an asshole kind of required being a Todd), she said he wouldn’t be able to balance two glasses of water on the backs of his hands. Obviously, he insisted he could and only realised what she was doing too late. When she’d placed the glasses there and he’d had a victorious smirk on his face, Marinette had simply kissed his cheek, winked and left, wishing him good night.

And then he was stuck there, hoping someone would rescue him because it wasn’t like he could ruin the carpet under the table. He couldn’t do that to _Alfred._ At around 4 am he was woken up by glass shattering when he’d accidentally moved his hands too much in his sleep. 

Fucking Pixie Pop. 

So well. If nothing else, he’d at least learnt to not mess with his little sister because she was one hundred per cent prepared to fight a war he started. 

(A week later, Marinette found an award with the text “The biggest asshole of the Todd family, the goddess of prank wars” on her desk. She framed it.)

**Author's Note:**

> I hope this was a fun read? Because how does one write siblings or humour?  
> (I've only got two siblings who are thirteen and seventeen years younger than me so like,,,)
> 
> Do come scream at me on my [tumblr](https://ethelphantom.tumblr.com/) if you feel like it!


End file.
